Both postprandial oxidative stress and derangements in carbohydrate (CHO) and lipid metabolism have been implicated in the development of complications in type 2 DM. Yet the ability of aerobic exercise to improve these derangements has not been fully explored. This study will examine the effects of an acute bout of aerobic exercise (30 minutes of treadmill walking at 65% VO2Max) in a group of physically untrained subjects with younger-onset type 2 DM and non-DM controls on: (1) CHO and lipid metabolism (glucose, insulin, C-peptides and triglycerides) following 3 meals; (2) postprandial oxidative stress (total MDA, F2 Isoprostanes, total hydroperoxides, vitamin A, E and carotenoids) and LDL susceptibility to oxidation (lag time, maximal conjugated diene formation) following 3 meals; and (3) oxidative stress and LDL susceptibility to oxidation 30 minutes after an acute bout of aerobic exercise. In addition, the relationship between baseline insulin sensitivity, antioxidant status, VO2Max and exercise-induced changes in oxidative stress, CHO and lipid metabolism will be explored. The study will include 35 subjects with type 2 DM (ages 18-40) with duration of diabetes (<7 years) and 35 non-DM controls who will participate in a nonexercise (NE) and an exercise (E) protocols, performed in random order at the General Clinical Research Center. Each of the protocols will be three days in duration. On the first day of either protocol, a glucose clamp will be performed for measurement of insulin sensitivity. On the second day of the E protocol, baseline parameters of oxidative stress, LDL susceptibility to oxidation and lipid metabolism will be obtained prior to an acute bout of aerobic exercise and periodically throughout the post exercise period, during which three meals will be consumed. On the second day of the NE protocol the same protocol will be followed without the acute exercise bout. On the morning of the third day of each protocol (24 hours after the E or NE session), fasting parameters of CHO, lipid and oxidative stress will be drawn. The diet will follow the National Cholesterol Education Program guidelines with 30% fat as energy, with 10:10:10% from saturated, monounsaturated and polyunsaturated fat, respectively with 1/3 of energy requirements consumed at each meal. This study represent a novel approach to the use of aerobic exercise in the treatment of type 2 DM, providing data for future investigations and exercise training studies in this area.